1. Field of the Invention
This invention generally relates to opaque insulated beverage dispensers with faucets for dispensing beverage and, more particularly, to such dispensers with a beverage quantity electronic display and related methods of determining and displaying quantity.
2. Discussion of the Prior Art
Beverage dispensers of the type that are specially fitted to directly receive freshly brewed beverage, such as freshly brewed hot coffee, from a mating beverage brewer are well known in the commercial brewing field. Such beverage dispensers, which may hold one half to two gallons of beverage, are adapted to be portable. After being filled with beverage, they are detached from the brewer and moved to a serving location. Individual servings are removed from the dispenser through manual actuation of a faucet located at the bottom in the case of a regular gravity feed dispenser or by actuation of a pressurization arm in the case of an airpot dispenser with an elevated faucet. Because the serving locations are often removed from any source of electricity, the beverages are kept warm solely by air gap, vacuum or fiber insulation within double walls of the dispenser.
During the filing of the dispenser with hot beverage, an inlet opening to a funnel facing upwardly from a top cover of the dispenser is located beneath and adjacent to a drain hole of a brew basket of the brewer. An outlet of the funnel within the interior of the dispenser body is connected to a down tube that extends vertically downwardly from the funnel outlet to location adjacent the bottom of the dispenser. The fresh beverage received in the funnel is channeled to the bottom of the dispenser by the down tube to enhance mixing. The inlet to the funnel is closed with a closure member after being removed from the brewer to prevent loss of heat, spillage and contamination.
A problem with such insulated dispensers is that they are opaque, often made from stainless steel or the like, and consequently it is not possible to determine how much beverage remains in the dispenser after service has begun without opening the top.
Accordingly, it is known to provide electronic displays of the level or quantity of the beverage within the dispenser body that is responsive to level sensors contained within the body. It has been know to attach such sensors to the down tube. In U.S. Pat. No. 6,741,180, issued May 25, 2004, to Zbigniew G. Lassota for an invention in “Beverage Dispensing Urn with Electronic Measurement Display”, which is hereby incorporated by reference, the sensors are resistive sensors mounted along the inside surface of the down tube at different levels to be detected and displayed. One sensor is beneath the lowest level being sensed and functions as a reference resistor that is intended to remain in contact with the beverage after the lowest level is sensed. In U.S. patent application Ser. No. 12/250,963 filed Oct. 14, 2008, by the present inventor and others, entitled “Beverage Dispenser with Level Measuring Apparatus and Method”, hereby expressly incorporated by reference, a double-walled, cylindrical resistive sensor is incorporated into the body of the down tube. In U.S. patent application Ser. No. 10/999,283 filed Nov. 30, 2004, by Zbigniew G. Lassota for an invention entitled “Air Pot beverage Dispenser with Flow Through Lid and Display and Method”, hereby expressly incorporated by reference, the sensors are capacitive sensor elements in the form of single capacitive plates that form capacitors with the beverage when the beverage is located at the same level as, and opposite, the capacitive sensor elements. The capacitance of a capacitive circuit changes as the beverage moves in and out of position adjacent and opposite the plate of the capacitive sensor.
A problem with this known capacitive-type level sensor is that the capacitances of the capacitors change with changes in temperature of the beverage to give a false reading. A problem with the resistive-type levels sensor is that the resistive, conductive element must be in direct contact with the beverage which can lead to corrosion and circuit failure. Also, in known sensing circuits have not been able to take advantage of existing off-the-shelf integrated circuitry. A problem with known capacitive sensing circuits is that their power consumption results in relatively rapid depletion of the battery. This is due in part to the use of relatively large capacitors that have been believed needed for accurate sensing and a failure to take advantage of the low power consumption, accuracy and reliability off-the-shelf micro-integrated circuitry.